title: Prediction of malignancy in cystic neoplasms of the pancreas: a population-based cohort study.
abstract: OBJECTIVE
  Pancreatic cystic neoplasms (PCNs) are being detected with increased frequency. The aims of this study were to determine the incidence of malignancy and develop an imaging-based system for prediction of malignancy in PCN.
  
  
  METHODS
  We conducted a retrospective cohort study of patients ≥18 years of age with confirmed PCN from January 2005 to December 2010 in a community-based integrated care setting in Southern California. Patients with history of acute or chronic pancreatitis were excluded. Malignancy diagnosed within 3 months of cyst diagnosis was considered as pre-existing. Subsequent incidence of malignancy during surveillance was calculated based on person-time at risk. Age- and gender-adjusted standardized incidence ratio (SIR) was calculated with the non-cyst reference population. Recursive partitioning was used to develop a risk prediction model based on cyst imaging features.
  
  
  RESULTS
  We identified 1,815 patients with confirmed PCN. A total of 53 (2.9%) of patients were diagnosed with cyst-related malignancy during the study period. The surveillance cohort consisted of 1,735 patients with median follow-up of 23.4 months. Incidence of malignancy was 0.4% per year during surveillance. The overall age- and gender-adjusted SIR for pancreatic malignancy was 35.0 (95% confidence level 26.6, 46.0). Using recursive partitioning, we stratified patients into low (<1%), intermediate (1-5%), and high (9-14%) risk of harboring malignant PCN based on four cross-sectional imaging features: size, pancreatic duct dilatation, septations with calcification as well as growth. Area under the receiver operator characteristic curve for the prediction model was 0.822 (training) and 0.808 (testing).
  
  
  CONCLUSIONS
  Risk of pancreatic malignancy was lower than previous reports from surgical series but was still significantly higher than the reference population. A risk stratification system based on established imaging criteria may help guide future management decisions for patients with PCN.
authors.affiliation: 1] Center for Pancreatic Care, Southern California Permanente Medical Group, Kaiser Permanente Los Angeles Medical Center, Los Angeles, California, USA [2] Department of Gastroenterology, Kaiser Permanente Los Angeles Medical Center, Los Angeles, California, USA.
authors.forename: Bechien U
authors.initials: BU
authors.lastname: Wu
authors.affiliation: Department of Medicine, Kaiser Permanente Los Angeles Medical Center, Los Angeles, California, USA.
authors.forename: Kartik
authors.initials: K
authors.lastname: Sampath
authors.affiliation: Department of Medicine, Kaiser Permanente Los Angeles Medical Center, Los Angeles, California, USA.
authors.forename: Christopher E
authors.initials: CE
authors.lastname: Berberian
authors.affiliation: 1] Center for Pancreatic Care, Southern California Permanente Medical Group, Kaiser Permanente Los Angeles Medical Center, Los Angeles, California, USA [2] Department of Gastroenterology, Kaiser Permanente Los Angeles Medical Center, Los Angeles, California, USA.
authors.forename: Karl K
authors.initials: KK
authors.lastname: Kwok
authors.affiliation: 1] Center for Pancreatic Care, Southern California Permanente Medical Group, Kaiser Permanente Los Angeles Medical Center, Los Angeles, California, USA [2] Department of Gastroenterology, Kaiser Permanente, Riverside, California, USA.
authors.forename: Brian S
authors.initials: BS
authors.lastname: Lim
authors.affiliation: 1] Center for Pancreatic Care, Southern California Permanente Medical Group, Kaiser Permanente Los Angeles Medical Center, Los Angeles, California, USA [2] Department of Gastroenterology, Kaiser Permanente, Downey, California, USA.
authors.forename: Kevin T
authors.initials: KT
authors.lastname: Kao
authors.affiliation: 1] Center for Pancreatic Care, Southern California Permanente Medical Group, Kaiser Permanente Los Angeles Medical Center, Los Angeles, California, USA [2] Department of Gastroenterology, Kaiser Permanente, Orange County, Kraemer Medical Center, Kraemer, California, USA.
authors.forename: Andrew Q
authors.initials: AQ
authors.lastname: Giap
authors.affiliation: 1] Center for Pancreatic Care, Southern California Permanente Medical Group, Kaiser Permanente Los Angeles Medical Center, Los Angeles, California, USA [2] Department of Radiology, Kaiser Permanente Los Angeles Medical Center, Los Angeles, California, USA.
authors.forename: Anne E
authors.initials: AE
authors.lastname: Kosco
authors.affiliation: 1] Center for Pancreatic Care, Southern California Permanente Medical Group, Kaiser Permanente Los Angeles Medical Center, Los Angeles, California, USA [2] Department of Surgery, Kaiser Permanente Los Angeles Medical Center, Los Angeles, California, USA.
authors.forename: Yasir M
authors.initials: YM
authors.lastname: Akmal
authors.affiliation: 1] Center for Pancreatic Care, Southern California Permanente Medical Group, Kaiser Permanente Los Angeles Medical Center, Los Angeles, California, USA [2] Department of Surgery, Kaiser Permanente Los Angeles Medical Center, Los Angeles, California, USA.
authors.forename: Andrew L
authors.initials: AL
authors.lastname: Difronzo
authors.affiliation: Department of Research and Evaluation, Kaiser Permanente Southern California, Pasadena, California, USA.
authors.forename: Wei
authors.initials: W
authors.lastname: Yu
authors.affiliation: Department of Research and Evaluation, Kaiser Permanente Southern California, Pasadena, California, USA.
authors.forename: Eunis W
authors.initials: EW
authors.lastname: Ngor
mesh_terms: D000368:Aged; D002140:California; D015331:Cohort Studies; D005260:Female; D006801:Humans; D015994:Incidence; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D010181:Pancreatic Cyst / Q000473:pathology*; D010183:Pancreatic Ducts / Q000473:pathology; D010190:Pancreatic Neoplasms / Q000145:classification / Q000453:epidemiology / Q000473:pathology; D011230:Precancerous Conditions; D011237:Predictive Value of Tests; D011379:Prognosis; D012372:ROC Curve; D018570:Risk Assessment; D012307:Risk Factors; D014057:Tomography, X-Ray Computed / Q000379:methods; D014463:Ultrasonography / Q000379:methods